In the pharmaceutical field there is the known need of a constant and precise monitoring of the storage and transport conditions of medicines, which allows to guarantee that they are not modified in their chemical and physical characteristics and are therefore capable of preserving their functional properties and cannot provoke possible undesired side effects when performing their therapeutical activity.
Medicines, with particular reference to those packaged in bottles or small vials, are generally stored in boxes which in turn are gathered in groups, for example on pallets. These pallets are usually transported from the manufacturing site to the distribution center located in the destination area, where the pallet is divided into the various boxes or single bottles so as to allow the delivery to the client, in this specific case for example hospitals, pharmacies, etc.
It is therefore particularly important that each bottle is controlled as to the risk of exposure to undesired temperatures. For many medicines it is fundamental that they are not exposed to a temperature below a minimum temperature threshold, same as a maximum temperature not to be exceeded during their whole commercial life, in that a freezing thereof would however have undesired effects on their therapeutical capacity. The typical suitable range for the storage of said products is in fact considered to be between the temperatures of 2° C. and 8° C.
This problem of controlling the temperature during the storage and transport of the products is not however limited to the pharmaceutical field. Other fields interested in that can be, for example, food, biotechnologies, botanics, chemistry.
Although various technical solutions have already been developed to monitor the exceeding of a maximum temperature threshold in an effective and timely manner, this problem has not yet been adequately solved as far as a minimum threshold is concerned.
It is of particular interest to find a solution suitable for application on single items, even of small size, without particular limitations caused by the shape of the item whose temperature is to be monitored. In other words, the problem could be effectively solved by developing a sensitive member in the form of a label, i.e. a member of small bulkiness as well as adaptable to various surfaces, possibly also not flat, of the item on which it will be applied.
Moreover, most of the distribution system bases its efficiency on the use of devices capable of monitoring the product to be moved during its whole life and, if possible, in real time and from remote. Such a monitoring, in general, is based on the use of radio-frequency devices applicable on different items, commonly known in the field as RFID labels (from Radio Frequency IDentification). It is therefore particularly advantageous that the solution for monitoring a possible minimum temperature threshold could be integrated with this type of system.
U.S. Pat. No. 6,848,390 discloses a device that allows the monitoring of the exposure to temperatures above the desired temperature. Its operation is based on a member made from a shape memory alloy, selected among those known in the field also as SMA (from Shape Memory Alloy), that acts as a member capable of responding to temperature in combination with a member capable of exerting a load function (indicated in the field by the term “bias”). Said SMA member acts as a mobile member for displaying the exposure to temperatures above the desired temperature.
However this device not only does not allow to monitor the possible exposure to temperatures below the desired temperature, but it also requires a complicated calibration process that must allow to control the thermal conductivity towards the SMA member, providing for the inside of the sensitive device to be maintained under vacuum conditions or, alternatively, to be filled with a thermally insulating fluid. This latter feature, however, implies a slow response of the device, thus rendering it unsuitable for the instantaneous monitoring of undesired temperatures. Moreover, the need to maintain vacuum or fluid containment makes quite difficult to scale down said device to a “label” type format and makes unpractical its mass manufacturing.
A different solution is disclosed in U.S. Pat. No. 6,837,620 showing a sensor suitable to indicate the exposure, even temporarily, to temperatures below a preset critical temperature. It exploits the transition from the austenitic phase to the martensitic phase of a SMA wire associated with a bias, that can be either a spring or another resilient member. Said resilient member, which is the bias applied to the SMA wire, is also described as being capable of assuring the non-return of the sensitive member to its starting position, thus allowing to maintain the indication of the occurrence of the undesired event even when the temperature has returned to acceptable values.
However also in this case there are disclosed solutions that are difficult to adapt to configurations of the “label” type in addition to being difficult to integrate with RFID monitoring techniques and, especially, unsuitable in view of a large scale use. In fact, one of the proposed embodiments provides the use of a spring as bias member with consequent limitations in terms of miniaturisation of the system, whereas the second embodiment presents a system for moving the visual display member that would not be suitable, without substantial modifications, to be put into communication with a control microprocessor suitable for remote monitoring.
The use of shape memory members as sensitive members is disclosed also in the US patent application 2009/0120106. However in this case the visual display system refers only to the exceeding of maximum temperature thresholds. Moreover, although it is described in one of its embodiments as a system that can be integrated with RFID systems, its production appears to be quite complicated in that it is based on aspects of electromagnetic shielding performed by the system between a RFID label and a receiving member (known in the field by the term “antenna”) associated therewith.
Finally, the international patent application WO 00/50849 although generically disclosing the possibility of use of shape memory members as sensitive members inside devices for remote monitoring, does not describe nor provide any teaching about how to achieve the above-mentioned integration. Moreover, said use does not stand out as preferred with respect to the multitude of solutions presented as potentially useful for sensoring purposes and described in the specification, which result all substantially equivalent within the wide and varied range of possibilities.
The present invention allows to overcome the limits of the prior art to obtain temperature-sensitive labels capable of visually displaying the exposure to temperatures below a threshold temperature Tc set as critical and that can optionally be integrated with remote monitoring systems.